


boom de yada

by some_stars



Category: Supernatural
Genre: Aftercare, Biting, Dom/sub, M/M, Orgasm Delay/Denial, Praise Kink
Language: English
Status: Completed
Published: 2015-02-17
Updated: 2015-02-17
Packaged: 2018-03-13 10:22:49
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,046
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3377963
Author URL: https://archiveofourown.org/users/some_stars/pseuds/some_stars
Summary: <blockquote class="userstuff">
              <p>"You know," Castiel said, as his palm skimmed down Dean's chest and lightly over his cock, "humans are one of the few primates that don't possess penis bones."</p><p>"...what?" Dean said.</p>
            </blockquote>





	boom de yada

**Author's Note:**

> I did my best to research and fact-check all the scientific and historical information in here, but also it's a short PWP so I didn't go digging through journals or anything. (Mostly.) If you find something wrong, please let me know (after reading the endnotes), and I'll correct it if possible.
> 
> Thanks to [Imogen](http://archiought.tumblr.com/) for starting all this nonsense by tweeting many wonderful penis facts, to [Betty](http://teapotsahoy.tumblr.com/) for reminding me about monotremes and discussing kangaroo vaginas with me, to [Mara](http://grandpadean.tumblr.com/) for encouraging and betaing and ensuring that Dean actually sounded Dean-like, and to [Ang](http://actualvampireang.tumblr.com/) for always cheerleading my ludicrous tomfoolery even though _she doesn't even go here._ She is also to blame for encouraging the title, which is of course from [this wonderful Discovery Channel ad](https://www.youtube.com/watch?v=at_f98qOGY0) (warning for a large spider at 0:41 and an octopus at 0:45).

"You know," Castiel said, as his palm skimmed down Dean's chest and lightly over his cock, "humans are one of the few primates that don't possess penis bones."

"...what?" Dean said.

"Penis bones," Cas said. "Most primates have them, although they're relatively vestigial. Other mammals have much larger ones."

His fingers played over Dean's cock, coaxing it to hardness, which wasn't taking very long even with the weird primate talk. He was already half-hard just from the anticipation, and from the heat of Cas's chest pressed up against his back, Cas's breath tickling over his skin as he murmured in Dean's ear. He dug his toes into the rumpled sheets where they were planted outside the V of Cas's spread legs. Somehow knowing what was coming made his body even more eager, leaping to attention under the faint, teasing touches.

They'd played around like this before. Cas enjoyed teasing him, and Dean liked getting strung out a little, because it always felt better if you built up and pulled back a few times before letting go--and also, yeah, because it was Cas doing the stringing, Cas pulling him back. But this was going to be more than a few times. 

"It's a fascinating structure," Cas said, and ran his free hand up Dean's thigh, petting the tensing muscles soothingly. "You see, human penises achieve rigidity entirely through the engorgement of erectile tissue with blood, so the penis has to become erect before penetration can take place."

"You really-- _ah_ \--think this is the best time for a biology lesson?"

Dean didn’t really expect an answer, and he didn't get one; Cas just _hmm_ ed and kept up that maddening, feather-light touch. When he pulled his hand away to reach for the pump bottle on the bedside table, it was almost--almost--a relief. "Now, in animals with penis bones," he continued, "the bone--the baculum, it's called--allows the penis to be inserted before the expansion of the erectile tissue. It also enables a more sustained copulation."

"So, uh, they can--" He cut himself off with a low grunt as Cas took him slickly in hand. "They can fuck without getting turned on first?"

"That's a rather anthropomorphic way of putting it, but yes," Cas said, "more or less. Some species mate that way."

"Doesn't sound like much fun," Dean said. Cas started twisting his wrist slowly back and forth, his fist rotating around Dean's erection with barely any up-and-down movement at all. It wasn't like fucking. It wasn't like anything, really, except weird, and tight, and wet. "Fuck," Dean groaned breathlessly, "fuck, c'mon--"

Castiel pressed a kiss just behind his ear, humming a little against his skin, and moved his hand faster, sliding it up and down as he twisted. "No," he said, "not yet. Not for a while, I think."

The words, and even more the tone of Cas's voice, warm and steady and utterly implacable, sent a shot of heat all through him. He felt his legs starting to tremble, his whole body tensing as he tried to hold still, because Cas had told him that first thing, right off. Rule number one.

Cas's left hand was still resting on his thigh; when Dean grabbed at it, Cas turned it over and laced his fingers through Dean's and let him hold on.

It went on like that for what seemed like hours, maybe days. Castiel would bring him right to the edge of coming, then slow down or--if Dean was too close--just take his hand away and wait while Dean whined and panted and muttered, _Cas, fuck, fuck,_ and squeezed his hand tighter. Over and over, asking Dean each time-- _You sound very close now, Dean. Do I need to stop?_ \--until Dean started volunteering information on his current pre-orgasmic status without being prompted, which earned him a kiss and a low, warm, _Good boy,_ because Cas always told him when he was good, always, even when it made Dean turn red and squirm and want to look away.

And the whole time, Cas kept up his monologue on weird dicks of the world. It wasn't exactly news to Dean that Castiel knew pretty much everything about everything, and if he'd ever stopped to think about it, it wouldn't have surprised him that 'everything' included an apparently endless supply of fascinating penis trivia. After all, Castiel had actually been around to watch evolution happen (or Dean thought he had, anyway; he was never totally sure how to reconcile Cas's stories about Neanderthals and lungfish with the stories about Eden and Babel, not to mention the fact that his own life for the past ten years had been one long exercise in Biblical literalism). And Cas was always so _interested_ in everything, so it only made sense that if some of his knowledge was relevant to the topic at hand--so to speak--he might share a few of the more fascinating tidbits with Dean.

None of this understanding could have prepared Dean for the reality of Cas jerking him off and informing him that-- _did you know, Dean?_ \--"some human cultures consider the penis bone of the raccoon to be a good luck talisman."

Or, "Only three percent of birds have any penis-like organ at all, mostly waterfowl. Almost all other birds mate via a maneuver referred to by scientists as the 'cloacal kiss'--an extremely romanticized description, I might add."

Or, "Proportionally, the barnacle has the longest penis of any organism on earth. A barnacle's penis can extend up to seven times its own body length."

It didn't stop with animals, either. "At one time," Cas said, spreading his legs to force Dean's thighs open a little wider, "all the bears on coats of arms in Switzerland had to be painted with bright red penises to prove they were male. A war once nearly broke out over the omission of a bear's genitals from a depiction in a calendar."

And, "Prehistoric humans carved dildos out of stone. The earliest example archaeologists have ever found is about thirty thousand years old, though of course the first one was created only a few days after the discovery of effective smoothing and polishing techniques."

("Oh, sure, of course," Dean echoed, and wondered if Cas had had a front row seat for that little breakthrough, back when he'd been attending all those Neanderthal poetry slams.)

There was more about dildos after that, including [a poem](http://andromeda.rutgers.edu/~jlynch/Texts/dildo.html) that Dean was definitely going to make Cas recite for him again later, because the parts he managed to hear over his own desperate whines sounded filthier than anything that many hundreds of years old had any right to be. Eventually, though, Cas found his way back to the genuine article.

"The non-placental mammals have developed some particularly interesting variants," he said, interrupting himself every few words to press a line of wet kisses along Dean's jaw and up behind his ear. "The penis of the echidna, for instance, has four heads, like little rosettes." Castiel hummed appreciatively. He sounded like he was gazing at the frigging Mona Lisa. "It's actually quite beautiful."

Dean had been about to ask what the hell an echidna was--or try, anyway--but the sheer what-the- _fuck_ -itude of this statement demanded a response, and the imagery distracted him enough to take the edge off for a minute. "Four heads? The hell does it need _four_ for?"

"The female echidna, like other monotremes and marsupials," Castiel said, "has two vaginas."

And, okay, he had no clue what a 'monotreme' was, but, "Holy fuck," Dean said. "Like, koalas? Kangaroos? _Seriously?_ "

"Very seriously," Cas said, and yes, that was definitely his Very Serious voice. Kangaroos, goddamn.

"But that still--why--" He waved his free hand around in a gesture that hopefully expressed the general concept of 'two is not four,' since he was having a hard time turning it into a real sentence right at the moment.

"Well, when the male is actually copulating with the female, two of the four heads retract," Castiel said, his thumb stroking the space just behind Dean’s balls.

This only led to more questions, but Dean decided to let it go. He could always google it later.

(Actually, he might google a lot of this shit later. He wouldn't entirely put it past Cas to be fucking with him about the barnacle thing. Where the hell would they even keep it?)

"Really," Cas said a little later, resting his hand on Dean's stomach for a minute while Dean tried to keep from twitching his hips up into thin air and also, maybe, to breathe, "the human penis is one of the less interesting examples of the genre, biologically speaking, except in terms of what it lacks. But your species has always had a strange fascination with it." He wrapped his hand around Dean's cock again. "At least, it seemed strange to me before."

Dean braced himself for another round, trying very hard not to wonder just how many more times Cas was going to do this before he was satisfied. If maybe he wouldn't stop. If he might just keep going until Dean broke, begged him, fucking cried--

He could make him stop, he knew. If he asked. And Cas would keep holding him, and get him off as fast as he wanted, and kiss him, and tell him how good he was. All Dean had to do was tell him to stop. But there was something about that idea of Cas pushing him--breaking him, just a little--something Dean didn't want to look at too closely, something he wanted more than he should.

He was pretty sure he wasn't gonna make Cas stop.

Cas was hard too, and that at least was reassuring; he had been for a while now, nestled tight against Dean's back. If Dean hadn't been able to feel it right there he almost wouldn't have guessed Cas was turned on at all. His voice sounded like he was narrating a nature documentary, like this was the damn _March of the Penguins_ and Cas was Morgan Freeman. Which was a really weird thought to have with Cas's hand on his dick, so Dean tried to stop having it.

"Guess our dick obsession makes a little more sense now, huh?" Dean said. He rolled his hips back and up and shivered with a swell of smug triumph and _want_ at the sound Castiel made in response, a soft little _uhh_ that barely made it out of his throat.

Cas nipped sharply at the back of Dean's neck. It didn't hurt much but it shocked him, the unexpected starburst of pain sending a shiver down his spine and making him gasp. "What did I say, Dean?"

The hardness in his voice was rigid but warm, something tight and comforting to press against. "Don't move," Dean said, and felt a wave of heat roll over him, his stomach twisting with a dizzy mix of pleasure and shame. He squeezed his eyes shut against it, or maybe just to feel it more, he didn't know, everything was weird like this. "I won't, I'm sorry, I won't anymore."

"Shhh, I know." Cas kissed the spot he'd just bitten, his lips brushing so lightly it sent a shiver all through him. "I know you'll try to be good. You always try your best for me. Right?"

Dean couldn't quite speak, but he nodded, shuddering as Cas's mouth whispered faintly across the back of his neck again.

"But it's true, I admit," Cas went on, "the ancient Greek phallic processions seem less absurd in retrospect. Well, no." He started to jerk Dean off with the steady rhythm Dean always liked best, lingering just a moment at the top of every stroke. "Constructing a massive artificial penis and parading it through the streets remains absurd. But I understand the impulse now. The desire to...celebrate."

"How...how massive are we talking, here?" His breath was starting to come in shorter bursts as his body geared up for the millionth time, constantly, stupidly hopeful. But maybe--Cas hadn't done this yet, at least not for this long; hadn't done it right, like he was trying to get Dean off. _Maybe he was trying to get Dean off._

Just thinking it shoved him suddenly, dangerously close, and he only just managed to hiss out a warning in time for Cas to pull his hand away again. The frustrated groan that escaped came out much louder than he expected, his voice catching partway through. Fuck, maybe he was going to cry. The sudden spike of fear at that idea made him lose it a little more. "Come on, Cas, just fucking-- _please--_ "

"No," Cas said, and bit him again--just another tiny nip, but on his throat, this time, which actually fucking hurt. "You agreed, Dean, remember? You don't come until I say." His right hand slid over Dean's own, where he'd been clutching his leg so tightly that his knuckles hurt when Cas took hold of his hand and forced them to unlock. "And I'm not finished with you yet."

Dean hissed out a shuddering breath and tried to control the frantic tremors that overtook him as Cas spoke. Every word seemed to hit him like a bullet, tiny explosions building inside him until he was totally overwhelmed.

"Fuck, I _can't--_ " He felt his toes curling again, his heart pounding so hard against his ribcage that he could barely breathe around it.

He had agreed, of course. He'd agreed a lot. And it wasn't like Cas hadn't been perfectly clear when he'd asked--so calmly, so straightforward and without any seduction at all--if Dean was interested. It was just, the idea of the thing--'edging,' according to Cas's internet research; 'really extended sadistic teasing,' Dean would have more accurately called it--the idea of putting himself in Cas's hands, letting him do what he liked for as long as he liked until Dean was a quivering desperate mess, had seemed a lot more like a fuzzy, white-hot fantasy at the time, and a lot less like the sharp-relief reality of actually doing it, being played with, denied over and over again, Cas touching him and touching him but never just fucking _giving_ it to him--

All right, so it was still pretty hot. He just wasn't sure how much more he could take without...bursting into flames, or something. Almost twenty minutes into it now and Dean felt like his whole body was tingling, alive and electric all over his skin, a wave of pulsing aftershocks rolling out from his dick every time Cas pulled him back.

"Do you want to stop?" Cas asked. There was no judgment in his voice, just a simple question. He waited patiently as Dean took a deep breath, let it out slowly, then another, before turning to meet his eyes.

"No," he said, softly. "Just. Uh. Can you kiss me for a minute?" He glanced down as he spoke, feeling--he wasn't sure. A little stupid, maybe. Off balance, something.

Cas's hand cupped Dean's jaw just right, like always, the spread of his fingers fitting like they were meant to be there. Dean closed his eyes and pressed into the touch for a second, then let Cas pull him in across the tiny space between them. It was soft, the careful press of their lips for what felt like a long time, until Dean's mouth slid open on a sigh and Cas pushed in a little bit, quick little swipes of his tongue that felt more sweet than dirty. 

"You can always tell me what you need," Cas said. He scratched lightly at the edge of Dean's jaw, his throat, just enough to make the faint hairs stand up and a delicious shiver run over the skin. "Okay?"

"Okay," Dean agreed. Cas's hand closed around him again and his hips tensed, starting to ache from the effort of holding still. He opened his eyes and turned to watch. He wanted to see, wanted to watch every second, every tiny shift of Castiel's fingers that he was usually too far gone to really notice.

After a couple strokes it became clear that the situation was starting to get a little sticky. Dean watched Cas pump some more lube into his palm and braced himself for the chill. It warmed up once Cas started moving, though, and oh, fuck, that looked good, Cas's fist moving up and down, the glistening red tip of his dick disappearing and reappearing and everything so tight and wet and _good,_ fuck-- Dean dug his fingers into Cas's thighs, and watched, and moaned, and didn't fucking move.

It didn't last, of course. Before he knew it he was gasping again, "Close, close, I'm close," and Cas was stroking all the way up and off once more. Dean's eyes tracked his hand helplessly, like maybe if he stared hard enough he could just _will_ it back down onto his dick. That strategy failed, but Cas did start touching him again, even if it wasn't nearly enough, just one finger brushing lightly over him. It helped, actually--in an infuriating, frustrating way that made Dean feel like his balls were going to implode, but it helped.

"About twenty feet long," Cas said suddenly, "though nowhere near proportionate in girth."

Dean tore his attention away from the faint, slow slide of Cas's fingertip up the underside of his dick, and said, "What?"

"The giant phalluses," Cas said. Dean could hear him smiling. "You asked how massive they were."

"Oh." Dean vaguely remembered that. "That's...pretty massive, I guess."

"Sometimes they were built to be moveable, so they could wag up and down as the procession went on. It took some impressive engineering." He actually did sound impressed, like he'd been there watching and admiring the can-do spirit of the ancient Greek giant fake dick engineers. He probably had. "There was a complex system of ropes and counterweights that could take up to a dozen men to operate, depending on the size of the phallus."

That finger kept moving, slow, slow, dragging up along the vein before starting back down, just as slowly, with only barely any more pressure behind it.

"So," Dean said, "what was the point of all this fancy dick engineering and the parades and everything? Were they, uh..." He trailed off, biting his lip to keep still as Castiel swirled his fingertip in a circle around his slit, just once. "Were they--" 

Cas made a quiet little approving noise when Dean's cock twitched under his touch. The sound hit him even harder than the touch, forcing a choked whimper from his lips, and he had to take a couple deep breaths to regroup.

"Were they worshipping some kind of ancient penis god?" he finally managed.

"Actually, unlike similar celebrations in many other cultures, the ancient Greek _phallika_ weren't associated with any fertility deity. Rather, they were a Dionysian ritual, a disruptive force of chaos. As the processions moved through the streets they would shout obscenities and insults, and in fact this practice eventually evolved into the earliest comedies."

"Comedy evolved from--a bunch of guys carrying around a giant wooden dick and--ah--yelling at people?"

"Indeed," Cas said. "And this kind of practice was hardly unique to the Greeks. Such periodic rituals of controlled chaos develop in many highly stratified societies. By allowing for brief but regular public inversion of the usual social hierarchy, these events ultimately reinforce it and bind the community together through the shared threatening experience of anarchic liminality, thus maintaining a stable system." He pressed his thumb against the top of Dean's cock on the next slide up, mirroring his finger underneath, and it was the weirdest sensation--surrounded but not, squeezed but desperate for pressure. Also, Cas had his other three fingers stretched out like he was daintily holding a teacup, which added a welcome touch of surreal hilarity to the whole experience.

Dean had given up any hope of keeping up with Castiel's history lecture somewhere around 'stratified,' choosing to focus on what was happening with his own present-day, non-artificial (but reasonably massive, he thought) phallus. One by one, Cas brought his other fingers back into play, until he was stroking them up and down Dean's cock with a weird pulling sensation, his palm cupping and twisting over the head as he moved. He fell silent, then, so Dean did too, and for a minute it was quiet except for their breathing--Castiel's, measured and even, though Dean could feel his heartbeat picking up with them pressed together like this, and Dean's, wet and shaky and sounding really, really loud. Louder when Cas let off the weird claw-hand stroking and started rubbing that spot on the underside, just below the head, tracing slickly back and forth with his index finger as his thumb played over the faint scar.

"Fuck," Dean said, "fuck, Cas, please..." He wanted to throw his head back against Cas's shoulder and _move,_ thrust and push and squirm and chase after more, something, anything. But he didn't. He _wouldn't._ And anyway, he couldn't look away. Cas's fingers were so big, long and careful--Dean watched his hands all the time but right now it felt like each tiny shift and twitch of those fingers was shaking him to pieces, like somehow watching Cas touch him made it better, more, bigger, something. He didn't know, he couldn't fucking think anymore--a throbbing heat bloomed behind his eyes, sudden and fast, and then everything blurred. He blinked, felt the wetness sliding down his face, as he struggled for each hitching breath and still couldn't stop _watching._

Cas slid his thumb up and over the tip, through the wet mess of precome that had been leaking steadily since maybe the second or third time Cas stopped him. He rubbed firmly back and forth a couple times, and Dean did jerk his hips at that, couldn't help it. It earned him another sharp little bite, harder this time, right on that spot just before his neck met his shoulder where Cas knew it felt so good Dean couldn't fucking handle it. A wordless cry tore out of him and it was crazy, it was-- _humiliating,_ god, that all it took was one hand and a little nibbling, a few minutes of teasing and Cas had him shaking, crying, dizzy with need. Had him _loving_ it. He felt his face burning, wanted to close his eyes, turn and press his face against Cas's throat and stay there.

"Please," he said again, his voice thick and wavering. He blinked past more tears, bit his lip.

Cas's left arm came down across his chest, holding him tightly. "No," he said--breathed, really, his lips ghosting over Dean's ear as he took him in hand and started to pump his fist again.

The noise Dean made--shocked and raw and weak, god, it sounded like somebody had punched him. He couldn't believe how much that fucking did it for him, just that, Cas telling him no, denying him. Making him wait but he _couldn't_ wait, his face was hot and wet and he'd never been this close in his fucking life.

He didn't want to come yet. He wanted to hold on, he wanted to be good but he couldn't, he couldn't, couldn't--

Then Cas went on, at a more normal volume, "You know, I remember when you invented circumcision. Those first ancient Egyptians who picked up a stone knife and sliced off their foreskins...even we were surprised, I have to say. Of course, later it became part of the covenant, but only after--"

Okay, that helped. That helped a little too much, actually. "Cas," Dean said, "Cas, no, what the hell--"

"It was practiced on adults back then, not infants. Or boys passing into manhood, depending on the culture, to prove their endurance of pain and--"

Dean burst out laughing, more than a little hysterically, and yanked Cas's hand away from his increasingly terrified dick. "No way," he said--choked out, really, he could barely catch a breath--"no fucking way, not _one more word_ about--stone _knives,_ Jesus Christ, oh my god..."

Eventually the giggling started to let up, and he made the mistake of looking up at Cas. Cas's brows were furrowed, and he didn't look hurt or anything but he was glancing back and forth between Dean's face and Dean's flagging, traumatized half-boner like he was genuinely baffled, and Dean lost it again.

"It's a fascinating history," Cas said, in the same tone of voice he used when Dean had to cut off an excited lecture on the storied provenance of some ancient mystical doohickey they'd dug up, or the little-known true etymology of certain common Enochian words in a spell they were using, or various other stuff that a lot of the time _was_ fascinating, sometimes really not, but either way Dean would've preferred the _Popular Science_ take on it, because Cas's version had lost him ten minutes and about fifty footnotes back.

Except this time he was talking about the fascinating history of _cutting up dudes' penises_ and maybe Dean really was crazy, because somehow, right now, it seemed like the most endearing goddamned thing Cas had ever done.

Dean twisted around--sort of flopped, to be honest, but at this point he felt he deserved a little leeway as far as looking smooth went--and cupped Cas's neck, sliding his fingers into his hair. "God," he panted, grinning, just a couple inches away from Castiel's own small, spreading smile, "I fucking love you, you know that?" He kissed Cas before he could answer, but then, it hadn't really been a question.

When Dean started to sit back, Cas cupped his face in both hands and pulled him back in, dropping kisses all over his face--his forehead, his chin, down the drying tear tracks on his cheeks, and one on each eyelid, even, which felt super weird but made Dean smile anyway. Finally Cas stopped but he didn't let go, just tilted his forehead against Dean's, one hand sliding up through Dean's hair. It was his right hand, so it was covered in drying lube, but Dean figured his hair was enough of a sweaty mess already that a little lube wouldn't make much difference.

"So," Dean said when Cas leaned back and looked like he was about to say something, "where were we?" He glanced down at his cock, which had recovered from its mortal terror and was half-hard again already. It was such a little trooper.

He looked back at Cas and immediately wanted to look away again, though he didn't. Cas's face was-- _shining,_ glowing with open admiration like Dean was something so special Cas didn't even have words for it. All these years and that look still made him squirm, still made him wonder just what Cas thought he was seeing. It had started to feel good too, though. It felt good now, made his stomach flip and his throat tighten up. Made him feel proud, maybe, a little bit, to be the one Cas looked at like that--like _Cas_ was proud of him, even if Dean didn't know for what.

Still, he had to duck away from it after a few seconds. He got himself turned back around and resituated before speaking again, not quite trusting his voice at first.

"Okay, so," he said, after settling back between Cas's legs, "new rule: no talking about circumcision during sex. Or any other kind of dick injury. Anything painful and penis-related in general, actually."

Castiel nodded. "I think I can work with that."

"Cool," Dean said. "So, are we going back to weird animal dicks, or what?"

"A boar's penis rotates rhythmically during copulation," Cas said, and started to jerk Dean off in slow motion again--with his left hand, this time. Dean took a deep breath and closed his eyes, letting his head fall back against Cas's shoulder. He could almost--well, not relax, because he could already feel the need starting to build again, but the edge of panic was gone.

"Rotates, huh?" He felt around for Cas's now free, still a little slippery right hand and interlocked their fingers. "I'm kind of jealous. I knew a chick once who had a vibrator like that." Another deep breath, another slow exhale. "Pretty sure she liked it better than men."

"Don't worry, Dean." Castiel's voice sounded rougher, like maybe this was finally starting to get to him. His left hand felt different, twisted at a different angle, something, whatever. "I like your non-rotating penis just the way it is."

"Glad to hear it," Dean said, grinning a little deliriously. "I mean, it's the only one I got."

Cas was quiet for a couple minutes, working Dean back up and holding him there again, and yeah, Dean didn't know if it was the horrified laughter break or the kissing or if he was just getting used to it, but he wasn't counting the seconds anymore. He felt kind of floaty: not any less needy, not any less like his body was starting to vibrate at a frequency only bats could hear, and he was vaguely aware that he'd started to cry again (though it didn't seem to matter as much, now). But he felt like he could maybe just ride the tension like a wave, let Cas take him up and down and melt into this heat, this coiling flexing spiral that was so close to coming, and so out of his hands.

It could have been another minute or another ten. There was no way to tell anymore, not with his whole world narrowed down to Cas's hand, Cas's mouth on his throat, Cas all around him, hot and slick and everywhere, everything. At some point, though, Dean realized he'd started moving, rutting up into Cas's fist with short little thrusts. His lips were parted, mouth open and loose, and every jerk of his hips tore a low grunt from his chest, a rough, animal sound. And Cas wasn't stopping him.

Dean opened his eyes and looked down and watched himself fucking Cas's hand like it was an honest-to-god miracle, or the best hottest porn he'd ever seen, or maybe both, or, oh, fuck, fuck, " _Please,_ " he said, barely able to gasp it out, "please, please, Cas, fuck, please let me come, let me please, I need it, _fuck--_ "

"Yeah," Cas said--almost sighed, low and quiet and pleased. Then, "No--no, almost. One more, a little more, okay?"

He waited for the shot of desperate panic to knock him down again, but it didn't come. There was a space inside him where that feeling wasn't, and it was filled up with Castiel, all of him was, no room left for panic or worry or even want, except what Cas wanted from him, and that was easy. He could do it. Cas wanted it so he could do it and Cas would tell him when he wanted something else and it was easy, even though it was so hard it was almost shaking him apart.

Dean nodded and turned to meet Cas's kiss, whimpering into his mouth. He was clenching Cas's hip with his free hand so tight he could feel his nails digging in, but Cas just kissed him harder and kept stroking, not too tight, added the little twist at the top of each stroke he always did when he wanted to get Dean off fast, make him lose it. It always worked. It was working now.

"So good," Cas breathed, and kissed him again, quick and hard. "Oh, you're so good, Dean, so good for me, just a little longer, you can do it--" Another kiss. Dean was shaking hard now, trembling at the edge. This was the longest Cas had made him hold it yet and he was sure he couldn't wait one more second, but he did, and then one more, and then one more. He pushed all his frantic desperation into his moans--and really he was sobbing, now, begging, the words spilling helplessly out of his mouth, _Cas, Cas, please, need to come, need it, please--_

He wouldn't even have been able to hear Castiel's voice over his own noise if Cas hadn't been murmuring it right into his ear. " _So_ good, look at you, trying so hard for me, love you so much--" He bent his head and bit that spot again, that good spot. Dean let out a strangled wail, jerking hard against Cas's mouth.

"Oh god please Cas _please fuck please--_ " He choked it off, couldn't breathe, couldn't think. He just _needed,_ needed to come, needed to wait, needed and needed and nothing else.

"Yes," Cas said, and then again, louder, "yes, now, Dean, come for me, oh--"

He didn't black out, exactly. He was pretty sure. He definitely felt Cas jerk hard--once, twice, and then he was coming hot and wet against Dean's back, his cock twitching in the sweaty hot little space between their bodies. But it was kind of fuzzy and far away. Dean felt kind of fuzzy. Red and warm and fuzzy, soft, but he didn't black out. He just...relaxed. For a while.

Eventually he started to hear Cas's voice again. It was low and soothing, and Dean thought he could feel it against his skin, as solid and warm as his hands petting Dean's chest and his arms, touching him all over. "...then, of course, there's the cetaceans..."

 _The what,_ Dean tried to ask, but his mouth wasn't all the way back yet and it just came out as a questioning _mmmuh?_ sound.

"Whales, dolphins, and porpoises," Castiel said. "Seagoing mammals. They evolved from land animals that returned to the sea, so their anatomy is especially fascinating."

When Dean opened his eyes, he saw Cas looking down at him, sweaty and pink and pleased. He couldn't help the matching smile that spread across his face. "Hey," he said.

"Hey," Cas said. "How do you feel?"

That was a good question. He had to think about it for a minute; everything was tingling and kind of--glowing, because he was still high from his super awesome orgasm, but Dean knew from experience and a few nasty pulled muscles that post-sex endorphins could cover up a lot of future badness.

He breathed for a minute and tried to take inventory. His face felt hot and swollen and his eyes were a little scratchy. He was _really_ thirsty. He definitely didn't want to try being vertical any time soon. And--he lifted a hand to touch it, carefully--the bite mark on his neck ached, because apparently Cas had really just gone for it. Dean didn't remember it hurting even a little at the time. Sex did weird shit to your body.

"I feel good," he decided finally. "Kind of like I just ran a marathon, but good."

"Good," Cas said, and handed him a water bottle. "Drink this."

He pushed himself up just enough to chug down half the bottle without waterboarding himself, then handed it off to Cas and flopped back down, rolling over to snuggle his head into Cas's thigh and letting out a satisfied hum when Cas started stroking his hair.

"So," Cas said, sounding hesitant for the first time all night. "Did you enjoy it?"

Dean snorted. "Are you kidding me? That was _awesome._ That was like...extreme sex. Olympic level handjobbing. Gold medal sex-having." A pleasantly exhausted shiver zipped down his spine as Cas scratched lightly over his scalp and down the back of his neck, fingernails ghosting over his skin. "Hell, even the East German judge was kinda impressed."

"That's a yes, then," Cas said. Dean flailed a hand up blindly behind him until it smacked something that was probably Cas's face.

"Yes," he said, snickering a little as Cas batted his hand away. "Yes, that's a yes. Oh, but, Cas? Just a suggestion, but maybe from now on don't bring up, uh-- _foreskin slicing_ during sex?" He winced just repeating the words. "Knives and dicks in the same sentence is kind of a mood-killer."

"Well," Cas said, "at the time it seemed like you could use the help."

"That. That was on purpose?" Dean craned his neck around to glare at him. "You sneaky little _shit,_ that was totally on purpose!"

Castiel rolled his eyes. "Honestly, Dean, I'm a little insulted by how easy it is to trick you into overestimating my naiveté. Although," he added, "the history of circumcision really is a fascinating topic--"

"New rule!" Dean yelped, because, no. No no no no no. " _New rule!_ "

"That was for during sex," Cas pointed out. "We're not currently having sex."

"You know what," Dean said, "let's just make it a general thing, okay? Like, all the time. Always. Forever."

Cas laughed at him. There was definitely more circumcision talk in Dean's near future. He'd have to figure out some kind of suitable revenge, but it could wait. He'd get to it later, maybe, when he was less sleepy and more capable of sustaining a grudge, or a complex thought.

He settled his head back into Cas's lap, his face half-smushed against Cas's thigh. "So," he said. "Cetaceans?"

"Cetaceans?" Cas repeated blankly.

"Yeah, you know. Seagoing mammal whatever things." Dean yawned. "What about them?"

"Oh," Castiel said, "right. Cetaceans." He paused for a minute, presumably to regather his whale-related thoughts. "Well, for one thing, the blue whale has the largest penis of any living animal in the world, but that's hardly surprising." He slipped back into his filmstrip narrator voice almost immediately. It was nice, especially now that it wasn't making Dean have upsetting sex thoughts about penguins. "It's the nature and function of the cetacean penis, not its relative size, that's of special interest. You see, despite no longer needing to walk, cetaceans have maintained their pelvic bones for millions of years. Human scientists used to think these bones were a useless remnant of life on land, but in fact cetaceans use the powerful muscles that attach there to control the shape and motion of their penises."

Dean had been drifting off, but that caught his attention. "Wait, what--control the shape?"

"To an extent. A dolphin's penis, for instance, is long and S-shaped at rest, but it can extend it and move it around, or use it to grasp objects."

" _Dolphins can grab stuff with their dicks?_ "

Cas made an _mm_ noise of confirmation, which wasn't nearly as much excitement as Dean figured this topic deserved. Dolphins! Grabbing stuff with their dicks! _That_ was the kind of thing they should make nature documentaries about. That was some seriously awe-inspiring shit right there.

It reminded him, actually, of a couple of the more... _specialized_ cartoons in his porn collection. He'd watched those movies plenty of times, but he still wasn't sure if he found them compellingly hot or just compellingly bizarre, or maybe both. Adding dolphins into the equation wasn't really helping.

Cas began to card his fingers through Dean's hair again, and Dean felt sleep tugging at him, but he wanted to stay awake. He wanted to stay here and let Cas pet his hair and tell him awesome weird things about penises forever.

"Come on," he said, nudging his head up into Cas's hand, "more dick facts. Educate me."

Cas let out a faint amused huff. "In ancient Rome, people hung wind chimes shaped like penises to bring good luck."

"Wind chimes," Dean repeated. "Wind chimes? Seriously?"

"Some of the depictions were remarkably creative," Cas said. "I recall one memorable example that had wings, legs, and an additional penis of its own."

"...no way," Dean said. "There is absolutely no way any of that is true." Dolphins with prehensile tentacle dicks was one thing, but there was no fucking way-- 

He stuck a hand out. "Phone?" With a brief, longsuffering sigh, Cas leaned over to the nightstand and got it for him. Dean opened up the browser and paused. "What'd you say this thing was called?"

"A tintinnabulum," Castiel said placidly.

Dean turned to look at him, narrowing his eyes. Then he googled _penis wind chimes._

Well, what did you know. "Huh," he said. He clicked to get more pictures and there right up top was [the one Cas had mentioned](http://i.imgur.com/PMaTjuS.jpg), with the legs and the wings and its own bonus dick. And-- "Oh, hey, look, it's got a third dick in its tail."

Cas took the phone back and peered at the photo. "So it does."

"Lucky winged triple-dick wind chimes. Wow." A huge, jaw-cracking yawn seized him halfway through the last word. He felt Cas's hand start to rub up and down his back again, warm and light, in a soothing, drowsy rhythm. "Humans are--" Another yawn. "Humans are weird, man."

"Very much so."

He let his head drop back down and closed his eyes, finally, unable to resist any longer. " 's 'at why you like us so much?"

"Yes," Castiel said, quietly. "Among other reasons."

"It's the dicks, isn't it," Dean said, aware he was half-asleep already but reluctant to let go. "You love me for my awesome, boneless dick."

"Go to sleep, Dean," Cas murmured, and he already was, barely even heard Cas saying it. He felt himself drifting off to the sound of his own slowing breath, the weight of Cas's hand on his back: in and out, back and forth. Safe and warm.

"It loves you too," Dean told him, or maybe only thought he did, "love you," and the last conscious thought he remembered was wondering if he was going to have weird dick-themed dreams now.

*

He did, as it turned out. All the tentacle dicks in his dream were attached to Cas, and one of them rotated.

The next day, he added five wildlife documentaries to their Netflix queue, including one on Creatures of the Deep. And if he happened to bump that one up to the top of the list, well. There was nothing wrong with a little appreciation for the wonders of nature.

**Author's Note:**

> I got many of my penis facts from Wikipedia, but I also consulted the following sources:
> 
>   1. [This blog post about echinda penises](http://scicurious.scientopia.org/2013/01/25/friday-weird-science-echidna-ejaculation-is-a-little-one-sided/). It has photos!
>   2. Csapo, Eric. "Riding the Phallus for Dionysus: Iconology, Ritual, and Gender-Role De/Construction." _Phoenix_ 51.3/4 (1997): 253-95. The procedural details of the _phallika_ were not the main topic and I only skimmed it anyway, so the various inaccuracies that I'm sure remain are entirely my own fault. It's actually a really neat article, by the way; you should check it out if you have any interest in classics or religious studies or gender or anthropology or just generally stuff that's interesting.
>   3. Betty sent me [this delightful blog post](http://blogs.discovermagazine.com/notrocketscience/2012/04/17/kangaroos-have-three-vaginas/) about how and why female marsupials have three vaginas, which is well worth reading, but I decided that since one of them only functions as a birth canal and not to receive sperm, it didn't really count for the purposes of Cas's explanation here.
>   4. Much of the cetacean information came from [this article about whale penises](http://time.com/3306405/whale-penis-pelvis/).
>   5. I originally learned about tintinnabula from [this post](http://flutiebear.tumblr.com/post/13332940564/skyelinepigeon-lemon-sprinkles-roman-good), which I found again when googling. I saved and reuploaded the image in case it ever disappears from Tumblr. If/when that link breaks, please let me know so I can reupload again!
>   6. I never did manage to work the penis-head fish into this thing, but if I had to learn about them then you do too, and you can do so [here](http://news.nationalgeographic.com/news/2012/08/120827-genitalia-head-fish-sex-animals-science/) and [here](http://www.newscientist.com/article/dn22023-zoologger-the-fish-with-its-genitals-on-its-head.html).
> 

> 
> I crave and welcome corrections if you find anything that is definitely, factually wrong. If it's something like "well that's more or less true but it's an oversimplification" or "the baculum actually has several other functions" or "the intromittent organs of birds and invertebrates aren't actually homologous to the mammalian penis" or "the dating of that supposed earliest dildo is disputed," you're still welcome to tell me but I'm probably not going to change anything, because at a certain point you just have to let the penis fic go, you know?
> 
> Come find me on [Tumblr!](http://some-stars.tumblr.com/) I post stuff and sometimes also things.


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